"Stocks are moving higher today on the back of decent earnings reports, but overall, I think investors are wondering whether the economic and market momentum that boosted stocks from last October through March is starting to fade," said Michael Sheldon, chief market strategist at RDM Financial Group.

Two reports released early Tuesday showed the housing recovery is still on shaky ground. S&P/Case-Shiller reported another decline for home prices in February, and the U.S. Census reported that new-home sales dropped 7.1% in March.

The S&P 500 (SPX) added 5 points, or 0.4%. Hershey (HSY, Fortune 500), which surged to a 7-year high, and Baker Hughes (BHI, Fortune 500) were among the top gainers. Both companies also topped first-quarter earnings estimates.

Shares of Netflix tumbled almost 14% Tuesday, a day after the company posted a first-quarter loss and issued a weak outlook.

Apple, the world's most valuable company, reported earnings after the market closed. Shares of the iPhone and iPad maker have been struggling lately, and finished Tuesday 13% lower since hitting an all-time high earlier this month.

World markets: Some of the political worries in Europe cooled Tuesday, a day after the Dutch prime minister resigned due to the collapse of his governing coalition. Despite his resignation, an auction of nearly €2 billion in bonds by the Netherlands went well Tuesday, sending yields of the nation's benchmark bonds slightly lower.

Spain, whose finances have also been a growing concern in recent weeks, also had a successful bond auction of nearly €2 billion. Its yields fell as well.

Economy: Home prices hit yet another post-bubble low, according to the February reading of the S&P/Case-Shiller Home Price Index. Prices were down 3.5% from a year earlier, at their lowest level since November 2002. The data came in slightly worse than the 3.4% annual decline expected by economists surveyed by Briefing.com.

About a third of the companies in the S&P 500 have reported results, and more than 75% have exceeded analyst expectations, according to Thomson Reuters. In a typical quarter, a little over 60% of companies beat estimates.

Meanwhile, shares of Big Lots (BIG, Fortune 500) plunged more than 24% after the company revised its first-quarter outlook for U.S. same-store sales, a key measure for retailers, lower from its March forecast. Last month, the discount retailer estimated same-store sales would rise between 2% and 4% during the first quarter. Now, Big Lots said it expects sales to be "slightly negative."